Dealmakers had their heyday in the 1980s. Today the power on Wall Street resides with money managers, who control huge and growing pools of cash amid an unprecedented wave of investment by the American public. A flick of some fund manager's wrist can send $100 million barreling in or out of a single stock. That kind of heft flattens a lot of resistance.
True to Wall Street form, the new titans are exploiting their influence. Mutual-fund manager Michael Price actively pushes for change at companies--Dow Jones is a recent target--in order to improve their laggard stock prices. Meanwhile, the California Public...